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A. G. HUMMEL 8v P.'A. GRAHAM. TELEGRAPHY. I

No. 442,808. Patented Dec. 16 18-90.

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NIT-ED STATES PATENT ADOLPll G. IIUMMEL, OF NE\V YORK, AND FRANK A.GRAHAM, OF

' BROOKLYN, NE? YORK. I I

TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 442,808, dated December16, 1890.

Application filed July 10, 1890. Serial No. 35812 70. (No model.)

To aZZ whom 7'25 may concern:

Be it known that we, ADOLPH G. HUMMEL,

of the city, county, and State of New York,

and FRANK A. GRAHAM, of Brooklyn, Kings county, State of New York, bothcitizens of the United States, have invented certain new and usefulImprovements in Systems of Telegraphy, of which the following is such afull,

rapid sending in the police or the railway serv- In addition to this wewish, also, to se-' cure accuracy in such work and to furnish meanswhereby any inaccurate work will be detected and theresponsibilityplaced where it belongs. To this end we provide for theprinting of all messages, whether general or- -(lers or of whatevercharacter, at both the transmitting and the receiving station. Thesystem can be employed not only for the service mentioned-that is,police and railway service-but wherever any institution or ,con-

cern requires quick connection between its several branches.

\Ve prefer to place our batteries at the central oflice, thus doing awaywith local batter- One of our batand the other has a metallic circuit,the two being common, so far as the line is concerned. The lineiscapable of being grounded through a switch at the central ofiice and isdesigned to becso when the central-office apparatus is set fortransmitting.

Our invention is illustrated in the accompanying drawing, which shows indiagram a central office and two substations.

A is the central office, and B and C are the two sub-stations. At thecentral office is a battery D, which is permanently grounded at G. Theopposite pole of the battery is connected to one brush 6 of thepole-changing transmitter E, and also to an anvil 2 of a ninepointswitch F, which is provided with three anvils numbered 1, three numbered2, and three numbered 3, corresponding to the three positions of theswitch The battery D is also joined through a bell H to one of theanvils of the same switch. From the central brush 6' of the pole-changerthe circuit passes to a ticker J, and thence to anvils 2 and 3 of theswitch. Another of the anvils, numbored 3, is joined to the brush e ofthe transmitter, and the third of that number is connected to ground G.The other anvils are dead-points except that numbered 1 at the left,which is connected to ground through a normallyropen key I. The movableparts of the switch are connected up as follows: It being understoodthat there is a second battery Kin the main circuit, but located at thecentral office, one pole of this battery is joined to the central arm fof the switch F, and from the other-pole extends the main wire 4. Theright-hand arm f of the switch F connects with the other main wire 5,and the remaining arm f is joined to the wire 4 beyond the battery K.Such is the apparatus and such are the connections at the centraloffice.

At the substation B wires 4 and 5 lead, respectively, to the arms land Zof the six-point switch L, the anvils or points of this switch, likethoseof the switch F at the central office, being numbered in twogroups,1, 2, and 3,de-

pending on the three positions of the switch.

Of the first group, point or anvil 1 is joined to 3 of group 2 throughabell M, the wire 6, which runs to 3, being a branch from the main wire'7, which runs from the said point 1 to the next sub-station, and thusmakes a continuous connection between the said anvil l and one of thearms of the switch at the said sub-station C. Another branch 8 from thesame main wire runs to a brush a on the sub -station pole changingtransmitter N. From points 2 and 3 of group 1 runs a common wire 9through a ticker S, and through an adjustable resistance 0 to thecentral brush it of the transmitter N. The brush n of the sametransmitter is connected to ground. The points 1 and 2 of the secondgroup are joined by a wire 10 to the main wire 11, running to the switchat the next sub-station, the said main wire being grounded at.substations B through a normally-opened key P.

The circuits and apparatus at succeeding sub-stations are identical withthose just described. At the last station on the line the main wireswhich would otherwise pass onto another station are joined together.

The tickers are operated in the usual manner, the proper character beingbrought into position for printing by a suitable number of impulsescaused by the pole-changing transmitter, while this in turn is of theusual kind, without any features of special novelty.

The drawing shows the switches and other parts in the proper positionfor calling. Suppose, now, that the central-office operator wishes tocall a sub-station. In that case he simply operates the keyI and closesa circuit through all the bells, as follows": From battery D to bell H,anvil 1, arm f, wire 5, arm Z, anvil 1, bell M, wire 7, through stationand baekcby wires 11 and to point 1,:arm Z, wire 4, and arm 1, anvil 1,key I to ground, andfrom ground back to the other pole of the battery D.Thus the operator at the central office can call any station and receivean.

answer when a sub-station operator manipulates his key. In that case,assuming that theoperator at station E answers with the key P, thecircuit will proceed directly from wire 11 to ground andthence back tobattery. The tickers are normally cut out. Having called and received ananswer, the operator at central turns his switch to the transmittingrpoints 3, while the switch L at station Bis turned to thereceiving-points 2. Then the transmitter E is made to operate the tickerat B: alternately over a ground-circuit from battery D and a metalliccircuit from battery K. The ground-circuit is as follows: Ground on oneside to battery, thence to and through transmitter l, ticker J, andpoint 3, arm-f, wire 5, arm 1, point 2, wire 9, ticker S, resistance 0,transmitter N, line-wire 7, and so on through one or more stations backby wires 11 and 10 through switch L, wire 4, arm f point 3 to ground.The metallic circuit goes from battery K to arm f, point 3, transmitterE, and ticker J, and from there by the same course as far as wire 4.,whence .it goes directly to the opposite pole of battery K. The localoperator in transmittingan original message or a reply will turn hisswitch to the three points, and the central-office switch will be turnedto the two points for receiving. This willcut out all the stationsbeyond that which is trans-. mitting at the time. Thus the circuit ofbattery D will be ground, battery, transmitterE and ticker, switch F,wire 5, arm Z, point 3, Wire 9, ticker and resistance, brush n,transmitte r-N, brush 17, and ground. The metallic circuitwill startfrom battery K, pass through the switch to the transmitter, and thenceby the same course to the local transmitter N. This last-namedinstrument being new in the position shown, the circuit proceeds bybrush n and wires 8 and 6 to the switch L, and back by wire 4 to theopposite pole of the battery K.

If the transmitting-station. happens to be the most distant station onthe line, the message will be received 011 his own ticker and all thebells between him and the central office will tap until the message isfully in The same will be true of the messages sent from the centraloffice to the most dist-ant station. The batteries D and K will bearranged with like poles opposed for obvious reasons.

Having now described our invention, we claim 1. In a system oftelegraphy,a central station and one or more'local stations connectedtherewith by a main circuit, a bell at each station normally in the saidcircuit, a ticker or equivalent receiving apparatus at each of thestations, and a pole-changer or equivalent transmitter also at eachstation, and aswitch at each station with a triple set of connections,one set being the normal one which throws the bells intocircuit,-another set capable of throwing in one pole of the transmitterand the ticker at the same station for receiving, and the third setcapable of throwing in both transmitter-poles and the ticker forsending, and a key in the bell circuit at each station, whereby it ispossible to call from either station, and whereby the message isrecordedat both the sending and the receiving stations, as set forth.

2. In asystem of telegraphy, a pole-changin g transmitter and a tickerat one station, a main circuit running to suitablereceiving andtransmitting apparatus at one or more connected stations, and a two-armswitch, the said arms being adapted to co-operate in two positions withtwo sets of anvils or points, the first set being the terminals of acircuit includingthe ticker and one pole of the transmitter at itsstation, and the second set being the terminals of a circuit includingthe ticker and both transmitter-poles, as set forth.

3. 111a system of telegraphy, a central station provided with twobatteries having like poles opposed and one of the said batteries beingpermanently grounded, a pole-changing transmitter at the same station, amain circuit leading to suitable receiving apparatus at one or moresub-stations, the connections from the batteries through the transmitterand the said local receiving apparatus extending to ground beyond thereceiving apparatus from one side or pole of the trans mitter andthrough a metallic circuit from the battery which is not grounded on theother side or poleof the transmitter.

In testimony whereof we have hereunto set our hands, this 25th day ofJune, 1890, in the presence of two subscribing witnesses.

AD OLPH G.. HUMMEL. FRANK A. GRAHAM.

Witnesses;

OHAs. .D. FOWLER, WILLIs FOXVLER.

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